There are known such systems for producing pneumatic radial tires as disclosed in Japanese Examined Patent Publication No. Sho 60-59856, Japanese Examined Patent Publication No. Sho 62-35381, and Japanese Unexamined Patent Publication No. Hei 2-25321, for example. The conventional systems have a station for forming an inner lining element of rubber chafers, a body ply or body plies, and beads, a station for forming an outer lining element of a base tread, a cap tread, and belts, a station for forming a green tire of the inner lining element and the outer lining element, and a vulcanizing station comprising a plurality of vulcanizers. These stations are disposed independently in a scattered pattern in the plant. Between these stations, there are disposed a plurality of feeding apparatus including manually operated carriage vehicles for feeding inner lining elements, outer lining elements, and green tires formed in the respective stations to next stations partly automatically, with operators' manual transporting actions involved in the overall feeding process.
In each of the above conventional tire production systems, body plies and belts separately produced in the plant and kept in stock are supplied to the station for forming inner lining elements and to the station for forming outer lining elements. The tire production system not only takes up a very wide space, but also makes for little efficiency to produce tires for the reasons described below.
Heretofore, tires have been manufactured on a mass-production basis. For example, body plies and belts are produced by continuously forming a wide and long sheet made up of a number of cords coated with rubber, cutting the sheet into a number of pieces of given dimensions, connecting the pieces into strips, winding the strips, and storing them as body plies and belts. The body plies and belts in stock are then delivered to a next process.
The above tire mass-production system appears to lend itself to efficient tire production. However, it requires not only large-scale facilities for producing the sheet, cutting the sheet into pieces, and winding the cut pieces, but also a large space for storing the sheet. As a result, the plant incorporating the tire mass-production system needs a large space and huge energy for its operation. Therefore, though the plant is designed for the tire mass-producing system, it costs too much to produce tires by the system and can not enjoy the advantages of mass production. Particularly, if the plant for producing tire components such as body plies and belts and the plant for forming tires are separate from each other due to geographic limitations, then it is difficult to reduce the overall cost of the tires because the cost of keeping the tire components in stock and the cost of conveying the tire components represent large proportions in the overall cost. Since the process of keeping the tire components in stock and the process of conveying the tire components are required to be performed between other tire producing processes, it is difficult to perform various quality control processes for protecting tire components against humidity, preventing sheet surfaces from becoming hardening, and keeping sheet surface clean. Thus, the failure to achieve desired quality control levels results in a low yield of tire products and a poor tire quality at the same time, disadvantageously.
The present invention has been made in view of the above problems with the conventional tire mass-production systems. It is a primary object of the present invention to provide a system for producing tires to increase productivity and quality without requiring a wide space in the plant.
Another object of the present invention is to provide a method of producing good quality tires at a low cost.